Failure rate of single-unit restorations on posterior vital teeth: A systematic review

SYSTEMATIC REVIEW

Failure rate of single-unit restorations on posterior vital teeth: A systematic review Kelvin I. Afrashtehfar, DDS, MSc,a Elham Emami, DDS, MSc, PhD,b Motahareh Ahmadi, DMD, MSc,c Samer Abi-Nader, DMD, MSc,d and Faleh Tamimi, BDS, MSc, PhDe Restorative treatments dominate the dental health services provided in both private and public clinics in the majority of industrialized and developing countries.1 Consequently, these treatments represent a significant financial burden for patients and healthcare systems, especially if they fail or need to be redone, and for this reason, they require careful planning to prevent undesirable outcomes. In dental practice, some clinicians find it difficult to select the best treatment when planning to restore a defective tooth.2-15 Treatment planning and decision making become even more complex and challenging when other risk factors are involved and can influence a restoration’s longevity. This could include tooth vitality,16 remaining tooth structure,17,18 parafunctional habits,19 or the presence of a removable partial denture.20

ABSTRACT Statement of problem. No knowledge synthesis exists concerning when to use a direct restoration versus a complete-coverage indirect restoration in posterior vital teeth. Purpose. The purpose of this systematic review was to identify the failure rate of conventional single-unit tooth-supported restorations in posterior permanent vital teeth as a function of remaining tooth structure. Material and methods. Four databases were searched electronically, and 8 selected journals were searched manually up to February 2015. Clinical studies of tooth-supported single-unit restorative treatments with a mean follow-up period of at least 3 years were selected. The outcome measured was the restorations’ clinical or radiological failure. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, the Cochrane Collaboration procedures for randomized control trials, the Strengthening the Reporting of Observational Studies in Epidemiology criteria for observational studies, 2 reviewers independently applied eligibility criteria, extracted data, and assessed the quality of the evidence of the included studies using the American Association of Critical Care Nurses’ system. The weighted-mean group 5-year failure rates of the restorations were reported according to the type of treatment and remaining tooth structure. A metaregression model was used to assess the correlation between the number of remaining tooth walls and the weighted-mean 5-year failure rates. Results. Five randomized controlled trials and 9 observational studies were included and their quality ranged from low to moderate. These studies included a total of 358 crowns, 4804 composite resins, and 303 582 amalgams. Data obtained from the randomized controlled trials showed that, regardless of the amount of remaining tooth structure, amalgams presented better outcomes than composite resins. Furthermore, in teeth with fewer than 2 remaining walls, high-quality observational studies demonstrated that crowns were better than amalgams. A clear inverse correlation was found between the amount of remaining tooth structure and restoration failure. Conclusions. Insufficient high-quality data are available to support one restorative treatment or material over another for the restoration of vital posterior teeth. However, the current evidence suggests that the failure rates of treatments may depend on the amount of remaining tooth structure and types of treatment. (J Prosthet Dent 2016;-:---)

Supported in part by a Knowledge Transfer Grant from the Network for Oral and Bone Health Research. a Teaching and Research Assistant, Division of Prosthodontics and Restorative Dentistry, Faculty of Dentistry, McGill University, Montreal, Quebec, Canada; Research Associate, Division of Oral Health and Society, McGill University, Montreal, Quebec, Canada; and Visiting Scholar, Department of Reconstructive Dentistry, School of Dental Medicine, University of Bern, Berne, Switzerland. b Associate Professor, Department of Restorative Dentistry, Faculty of Dentistry, University of Montreal, Montreal, Quebec, Canada. c Research Assistant, Oral Health and Rehabilitation Research Unit, Faculty of Dentistry, University of Montreal, Montreal, Quebec, Canada. d Division Director and Associate Professor, Division of Prosthodontics and Restorative Dentistry, Faculty of Dentistry, McGill University, Montreal, Quebec, Canada. e Associate Professor, Division of Prosthodontics and Restorative Dentistry, Faculty of Dentistry, McGill University, Montreal, Quebec, Canada.

THE JOURNAL OF PROSTHETIC DENTISTRY

1

2

Volume

Clinical Implications The greater the amount of tooth structure, the better the performance of restorative materials. In posterior vital teeth, amalgam restorations seem to perform better than composite resin restorations, and crowns may be preferred over direct restorations when fewer than 2 remaining coronal walls are available.

In an evidence-based practice, clinicians should consider their expertise, the patient’s preference and financial situation, and the empirical research evidence. There is a real need to attend to current research because prosthetic and restorative malpractice claims constitute most dental litigation21; these claims are usually the result of non-evidence-based, unjustified treatments, or excessive treatments with crown prostheses rather than direct restorations.22 However, to the best of these authors’ knowledge, few up-to-date, evidence-based guidelines are available to help clinicians in this process. The purpose of this systematic review was to address this knowledge gap by answering this research question: Is there any difference in the failure rate of single-unit prostheses versus direct restorations in vital posterior teeth with sufficient remaining structure? MATERIAL AND METHODS This systematic review was conducted according to the guidelines of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement.23 The search strategy was developed with the help of 2 experienced librarians. Articles published between January 1993 and February 2015 were searched, with no language restriction, by using Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) through the Cochrane Library; MEDLINE through Ovid and EMBASE through Ovid (Supplemental Tables 1-4). In addition, 8 selected journals and the references of all identified studies were also searched manually (Supplemental Table 5). We included all relevant clinical randomized controlled trials (RCTs), quasiexperimental studies, and observational studies in which vital posterior permanent occluding teeth (population) were treated with either single complete crowns (intervention) or direct restorations (comparison) and followed for at least 3 years (time) to report the failure rate (outcome). Failure was defined as any complete or partial loss of the restoration that required replacement or repair.24 Reports were excluded if they failed to report tooth vitality and the number of remaining coronal walls or restored surfaces. Reports were also excluded if the studies did not differentiate among anterior teeth, third molars, or the primary dentition; or included periodontally compromised teeth; THE JOURNAL OF PROSTHETIC DENTISTRY

-

Issue

-

Initial electronic search n=4292

Articles after duplicates removed n=3241

Hand-search, articles not repeated n=67

Individual selection considering exclusion criteria by two reviewers (abstract search) n=3308

Abstracts selected for full-text review n=86

Full-text review of articles by two reviewers n=86

Full-text articles excluded by two reviewers n=54 (Not meeting the inclusion criteria = 28, inadequate data = 26)

Individual selection of final records by two reviewers n=27

Studies included in the synthesis n=14 Figure 1. Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) flow diagram of study selection process.

reported indirect restorations other than tooth-supported complete crowns such as inlays or implant crowns; had a pool of participants in which more than 25% were bruxers; or restorations were placed on removable partial denture abutments. After deleting duplicates, the 2 reviewers (K.I.A., M.A.) independently screened the titles and abstracts identified through the initial search and selected eligible articles for full review (Fig. 1). Intrareviewer calibration was carried out using the Cohen kappa test. The kappa coefficient was 0.90, indicating an “almost perfect” agreement25 between the 2 reviewers. Disagreements were discussed and resolved by consensus. The full copy of all potentially relevant studies was retained for a full assessment. Data extraction, quality assessment, and risk of bias assessment are detailed in Supplemental Material section Methodology. The data retrieved were organized into subgroups according to the type of restoration and number of Afrashtehfar et al

-

2016

3

Table 1. Summary of characteristics of included 14 definitive studies

Study (Year)

Country/ Setting

No. of Mean Age/ Study Patients/ Age Design/ No. of Range at No. of Follow-up Restorations Baseline Teeth Remaining (y) at Baseline (y) Restored Walls

Type of Restoration Material

% Dropouts/ Restorations

Funding

6.9/ -

Public institution

0/0

Voco, Cuxhaven

Randomized controlled trials Bernardo et al2 (2007)

Portugal/Uni

RCT/7

507/1748

Kramer et al3 (2011)

Germany/Pri

RCT/6

Manhart et al4 (2010)

Germany/Uni

9.9/8-12

Premolar; Molar

0-4

Amalgams; Resins

30/66

32.9 /24-59 Premolar; Molar

2-3

Resins (2 types)

44.3/19-67 Molar

RCT/4

43/96

Plasmans and van ’t Hof5 The Netherlands/ (1993) Pri-Uni

RCT/4

130/300

32/17-54

Shi et al6 (2010)

RCT/3

32/100

20.5/ -

Premolar; Molar

4

183/1544

22.5/ -

Premolar; Molar

2-3

China/Uni

Molar

1-4

2 Resins (2 types)

14/13.5

Dentsply DeTrey

0-1

Amalgams (different retaining methods); Amalgams with posts

0.8/1.3

Public and Cavex Holland

- /20

NR

Amalgams (3 types)

8.7/8.4

Public institution

Resins

6.1/ 6.4

NR

Resins (2 types)

Observational studies Akerboom et al7 (1993)

The Netherlands/Uni Prosp/10

Kiremitci et al8 (2009)

Turkey/Uni

Prosp/6

33/47

34/ -

Premolar; Molar

3

Kohler et al9 (2000)

Sweden/Pub

Prosp/5

45/63

26/11e63

Premolar; Molar

2-3

Resins (2 types)

11.11/7.9

Public institution

Kolker et al10 (2004)

USA/Uni

Retrosp/10

518/756

54.5/20-79 Premolar; Molar

0, 1

Amalgams; Crowns (on amalgam)

31.5/ 31.5

Public institution

Kopperud et al11 (2012)

Norway/Pub

Prosp/4.6

NR/3470a

15.3/6e57 Premolar; Molar

3

Amalgams; Resins (4 types)

28.7/27.2

Public institution

Lin et al12 (1997)

China/Uni

Prosp/3

Resins (5 types)

- /26

NR

Lucarotti et al13 (2005)

England/Pub

Retrosp/11 NR/300 480a

Mjor & Jokstad.14 (1993)

Norway/Pri

Prosp/5

Opdam et al15 (2004)

The Netherlands/Uni Retrosp/5

NR/169

- /15-52

Premolar; Molar

4

- /18-80

Premolar; Molar

2-4

Amalgams

NA

Public institution

NR/179a

13/ -

Premolar; Molar

3

Amalgams; Resins

- /18.8

NR

382/703

- /22-78

Premolar; Molar

1-4

NA

NR

Resins

NA, not applicable; NR, not reported; Pri; private practice; Prosp, prospective; Pub, public clinic; RCT, randomized control trial; Retrosp, retrospective; Uni, University. aInformation not relevant to our review (glass ionomers and/or compomers) is not included in the table. Maximum follow-up for all groups is reported.

remaining tooth walls. For each subgroup, the outcome was treated as a continuous variable (0%-100%) reported weighted arithmetic mean (WAM) 5-year failure rate calculated using the following formula: Pn w i xi e x = Pi=1 ; n i=1 wi where xi = the average of sample i, and wi = size of sample i. A metaregression model was used to assess the correlation between the number of remaining tooth walls and the WAM 5-year failure rates of the restorations. This was done for RCTs and observational studies combined and separately. All analyses were performed using statistical software (SAS v9.3; SAS Institute)26 (a=.05). RESULTS The electronic and manual search yielded 3241 articles after removal of duplicates (Fig. 1). An additional 67 articles were obtained from the manual search of the references of review articles identified within the initial Afrashtehfar et al

search. Of these 3308 articles, 3227 were excluded after screening the titles and abstracts, and 54 were further excluded based on eligibility criteria (Supplemental Table 6). From the remaining 27 articles, only 6 were genuine publications that had only 1 published manuscript per study2,6,8,11,12,14; however, the remaining 21 articles included 13 follow-up publications of 8 genuine studies (Supplemental Table 7); 3 studies3,4,9 were reported in 2 publications each, 4 studies5,7,10,15 were reported in 3 publications each, and 1 study13 was reported in 6 publications. After the redundant publications were removed, only 14 studies2-15 were included (Table 1). They consisted of 5 RCTs2-6 and 9 observational studies, of which 6 were prospective79,11,12,14 and 3 were retrospective.10,13,15 Study outcomes were presented as the number of restorations lost, retention rates, cumulative failure rates (%), or modified United States Public Health Service (USPHS) criteria scores. The WAM 5-year failure rate for each specific condition indicated that the failure rate was higher in teeth with less remaining structure (fewer than 2 remaining walls) (see Fig. 3D). These differences were THE JOURNAL OF PROSTHETIC DENTISTRY

4

Volume

+ Adequate

? Unclear/not specified

– Inadequate

Sequence generation

Concealment of allocation

Handling of withdrawals

Intention-to-treat-analysis

Blinding: outcomes assessment

Not applicable/not feasible

Bernardo 2007

?

?

?

+

Kramer 2011

?

?

+

?

?

C

Manhart 2010

+

+

+

?

+

B

Plasmans 1993

+

?

+

+

Shi 2010

+

?

+

+

C +

Level of Evidence

C

B

A Sequence generation Concealment of allocation Handling of withdrawals Intention-to-treat analysis Blinding: assessment 0

20

40

60

80

Risk of Bias (%)

100

B

Figure 2. Risk of bias. A, Risk of bias summary: review authors’ judgments about each risk of bias item for each included study. B, Risk of bias graph: review authors’ judgments about each risk of bias item presented as percentages across all included studies.

more pronounced for composite resins than for amalgams or crowns. Composite resins had a significantly higher failure rate than amalgams, regardless of the remaining tooth structure (P<.05) (Supplemental Table 8). In teeth with fewer than 2 remaining walls, direct restorations presented significantly higher failure rates than crowns (P<.05) (Supplemental Table 9). The quality risk of bias assessment for RCTs is presented in Figure 2, and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE)-based quality appraisal for observational studies is available in Supplemental Table 10 and Table 2. Among the 5 RCTs included, the sequence generation, concealment of allocation, handling of withdrawals, intention-to-treat THE JOURNAL OF PROSTHETIC DENTISTRY

-

Issue

-

analysis, and blinding were adequate in 3, 1, 4, 3, and 2 studies, respectively (Fig. 2A). The risk of bias across studies is presented as percentages in Figure 2B. The handling of withdrawals and drop-outs was adequately described in 4 studies.3-6 The estimated risk of bias was considered moderate (intermediate level of evidence) in 2 studies4,6 and high in three studies.2,3,5 Regarding study design assessment following the American Association of Critical-Care Nurses (ACCN) level of evidence (where A is the highest level and M the lowest),27 3 RCTs2,3,5 were ranked as C (low level), and 2 RCTs4,6 were classified as B (moderate level) (Fig. 2A). Among the 9 observational studies included, 3 studies10,11,13 were classified as high level of quality of reporting according to the Olmos criteria,28 5 as moderate level,7-9,14,15 and 1 as low level (Table 2).12 Most observational studies presented deficiencies (partial or incomplete) according to the STROBE criteria in reporting the following items: title and abstract, study design, variables, main results, additional analyses, generalizability, and funding. In contrast, the remaining sections of the STROBE criteria were met in most of the studies (Supplemental Table 10). The study design level of evidence was ranked as C for all included observational studies according to ACCN’s criteria (Table 2). From the 14 selected studies, a total of 308 744 direct and indirect restorations were identified. Of these restorations, 358 were single crowns, 4804 were composite resins, and 303 582 were amalgams. The sample size of each study ranged from 478 to 300 470 restorations.11 Participants included in each study ranged from 30 to 82 537.3,13 The age range of participants in these studies varied between 6 and 80 years of age.11,13 The mean age of participants across the studies was 29 years old, although this did not take into account 3 studies in which the mean age was not extractable13,15 or the number of participants was not reported.12 Drop-out ranged from 0%3 to 31.5%.10 Participants were recruited from dental clinics across various universities,2,4-8,10,12,15 private offices,3,5,14 and public health centers.9,11,13 Of the 14 included studies, 2 studies reported support from private companies3,4 and 6 from public institutions,2,7,9-11,13 1 study reported financial support from both a private company and a public institution,5 and 5 studies did not report any sources of support.6,8,12,14,15 Twelve studies examined restorations in molars and premolars and 2 studies4,5 only in molars. Seven studies3,4,6,8,9,12,15 assessed only composite resin restorations and 3 studies5,7,13 only amalgams. Three studies2,11,14 compared amalgams with composite resins, and 1 study10 compared amalgams with crowns. All single crowns were retrieved from 1 study,10 63% of the composite resins were reported by 1 study,11 and 99% of the amalgams included were reported by 1 study.13 Most of the studies (10 of 14) were located in Europe; 4 studies were located in the United States,10 Turkey,8 Afrashtehfar et al

2016

5

50

50

45

45

Five-year WAM Failure Rate (%)

Five-year WAM Failure Rate (%)

-

40 35 30 25 20 15 10 5

35 30 25 20 15 10 5

0

0 Four walls Three walls

Two walls

One wall

Remaining Tooth Structure

Four walls Three walls

Less than a wall

A

50

50

45

45

40 35 30 25 20 15 10 5

Two walls

One wall

Less than a wall

B

Remaining Tooth Structure

Five-year WAM Failure Rate (%)

Five-year WAM Failure Rate (%)

40

40 35 30 25 20 15 10 5

0

0 Four walls Three walls

Two walls

One wall

Remaining Tooth Structure Amalgam restorations

Less than a wall

Four walls Three walls

C

Two walls

One wall

Less than a wall

Remaining Tooth Structure

Composite resin restorations

D

Crown prostheses

Figure 3. Graphic representation of 5-year accumulated failure rate of restorative treatments according to remaining coronal structure in vital teeth. A, Data pooled from both observational studies and randomized controlled trials (RCTs). B, Data from Fig. 3A without influencing studies (Kopperud et al11 and Lucarotti et al13). C, Data from only observational studies. D, Data from only RCTs. WAM, weighted arithmetic mean.

and China.6,12 All included studies were published in English, except for one,12 which was reported in Chinese. All included studies were published between 19935,7,14 and 2012.11 A wide range of follow-up (3 to 10 years) was reported across all the included studies. DISCUSSION Discerning whether a direct or an indirect restoration is the better treatment option requires an assessment of possible confounders. To our knowledge, this is the first Afrashtehfar et al

systematic review of the clinical failure of restorations in posterior permanent vital teeth that considers the number of remaining walls as a key risk factor, rendering it very relevant for clinical decision-making. Fourteen studies2-15 involving 308 744 restorations and over 1902 patients were included in this review; 2 of the 5 RCTs4,6 (Fig. 2A) and 3 of the 9 observational studies10,11,13 were judged as having low-risk of bias (Table 2). The RCTs showed that in teeth with fewer than 2 remaining walls, crowns were better than amalgams, and regardless of the remaining tooth structure, THE JOURNAL OF PROSTHETIC DENTISTRY

6

Volume

-

Issue

-

Table 2. Overall quality appraisal of observational studies included

Study, Year, Location

No. of Applicable Quality Appraisal Criteria Fulfilled (%)

Classification of Report According to Olmos et al28

Level of Evidence According to AACN’s New Evidence-Leveling System27

Akerboom et al7 1993, The Netherlands

11 (50)

B

C

Kiremitci et al,8 2009, Turkey

12 (55)

B

C

Kohler et al,9 2000, Sweden

13 (59)

B

C

Kolker et al,10 2005, United States

21 (96)

A

C

Kopperud et al,11 2012, Norway

20 (91)

A

C

Lin et al,12 1997, China

10 (46)

C

C

Lucarotti et al,13 2005, England

19 (86)

A

C

Mjor et al,14 1993, Sweden

12 (55)

B

C

Opdam et al,15 2004, The Netherlands

17 (77)

B

C

Olmos classification criteria: A, high level, study in agreement with more than 80% of the STROBE criteria; B, moderate level, 50%-80% of STROBE criteria were fulfilled; C, low level, less than 50% criteria could be achieved. ACCN level of evidence: C, qualitative studies, descriptive or correlation studies, integrative reviews, systematic reviews, or randomized trials with inconsistent results. AACN, American Association of Critical Care Nurses; STROBE, Strengthening the Reporting of Observational Studies in Epidemiology.

amalgams presented better outcomes than composite resins. We discuss the treatment options according to the remaining tooth structure below. Teeth with 4 remaining walls The data retrieved seemed to indicate that amalgam restorations might be the better option in teeth with 4 remaining walls, although composite resins also performed well in this situation. The only RCT2 that directly compared amalgams to composite resins and another RCT6 that did not compare them directly indicated that composite resins presented a significantly higher failure rate than amalgams (Fig. 3D). Surprisingly, the data of the 3 observational studies (which did not directly compare composite resins with amalgams) presented the opposite results (P<.05) (Fig. 3C). This was probably because 2 of these observational studies only reported amalgam restorations, and they were extremely large. This rendered the data for amalgams 80 times the data available for composite resins (Table 2).11,13 Interestingly, the WAM values calculated without these 2 influencing studies11,13 confirmed the RCTs showing that amalgam failure rate was lower than that of composite resins (Fig. 3B). No information was available for crowns for teeth with 4 remaining walls (Table 3), probably because of the “sound tissue preservation principle,” where harming the remaining tooth tissue would be unjustified because sufficient structure exists to support a direct restoration.29 In addition, this could be related to patients’ financial constraints or preference. Indeed, an important benefit of using direct restorations instead of crowns is the lower cost and ease of access for vulnerable populations.30 Teeth with 3 remaining walls The evidence gathered suggests that amalgams are the best choice in teeth with 3 remaining walls (Fig. 3B, D). The only RCT2 comparing composite resins with amalgams in teeth with 3 remaining walls concluded that the amalgams failed 2 times less often than composite resins THE JOURNAL OF PROSTHETIC DENTISTRY

(Fig. 3D). This is in agreement with a previous narrative review that advised against using composite resins in posterior multisurface restorations.31 The observational studies presented contradicting results (Fig. 3C) but were of lower quality than the RCT and presented 45 times less data on composite resins (Table 3). No information on crowns in teeth with 3-remaining walls was available, probably because of the same sound tissue preservation principle mentioned above. Teeth with 2 remaining walls Again, amalgams seemed to be the material of choice. All RCTs agreed that amalgams present better outcomes than composite resins in teeth with 2 remaining walls (Table 3; Fig. 3D), and this is also in agreement with a previous narrative review.31 The observational studies opposed the results of the RCTs (Fig. 3C), but there were no direct comparisons between amalgams and composite resins in the observational studies (Table 3). No information was available on crowns for teeth with 3 remaining walls. Teeth with 1 remaining wall The studies included here suggested that crowns were the best choice for vital teeth with 1 remaining wall, followed by amalgam restorations. The only RCT2 comparing amalgams with composite resins in this scenario showed that amalgams outperformed composite resins (Table 3; Fig. 3D), and the only observational study comparing crowns with amalgams reported 4 times more failures in amalgams (Table 3; Fig. 3C).10 Similar conclusions were made by pooling data from studies not making direct amalgam-crown comparisons (Fig. 3A, B). Teeth with less than 1 remaining wall RCTs comparing composite resin restorations with amalgams on vital teeth with less than 1 remaining wall showed that composite resins failed twice as often (Fig. 3D); moreover, an observational study10 comparing Afrashtehfar et al

-

2016

7

Table 3. Failure rates of tooth restorations in vital teeth according to remaining tooth structure Amalgam Ref

Resin

Crown

F (y)

N

Failure %

Ref

F (y)

N

Failure %

Ref

5a,b

4

255

10

2a

7

12

50

10a

a

5

398

48

10a

10a

10

255

63.9

2a,b

7

11

18.2

5a,b

4

255

10

2a,b

7

12

50

10a

a,b

7

11

18.2

4

4

13

7.7

10a

10a

5

398

48

15

5

60

18

10a

10

255

63.9

48b

10

658

12.1

9b

5

9

33.3

b

7

78

11.5

2b

7

74

33.8

F (y)

N

Failure %

5

358

12.3

10

263

22

5

358

12.3

10

263

22

Less than a wall 10

One wall 2

Two walls 2

13

5

60 295

40

3b

6

16

0

13

10

60 295

57

4b

4

17

5.9

7

10

777

9.4

15

5

95

27

Three walls 48b

10

459

8.5

9b

5

49

26.5

2b

7

338

9.5

2b

7

356

19.4

13

5

163 767

36

8

6

44

4.5

13

10

163 767

51

14

5

36

16.7

14

5

33

9.1

11

4.6

2800

12.4

11

4.6

135

17.8

3b

6

52

0

7

10

648

4.9

4b

4

40

5

15

5

266

14

Four walls 2b

7

429

1.2

2b

7

450

6.4

13

5

76 418

28

12

3

125

14.4

13

10

76 418

42

7.7

4b

4

13

15

5

282

7

6b

3

80

7.5

Gray area indicates no studies were found reporting these conditions. F, follow-up in years; N, number of restorations; Ref, reference of study. aStudy repeated on 1 and less than 1 remaining wall without discriminating between these scenarios. bReferences of RCTs.

amalgams with crowns reported that crowns were better (Tables 2, 3; Fig. 3A-C). Accordingly, in teeth with less than 1 remaining wall, crowns may be the best treatment option. However, dental implants should also be considered, as implants have a lower failure rate (6%-10% at 5 years) than crowns on teeth missing all their coronal structure.32 Another important finding in our study was that, regardless of the treatment used, restorations failed more often in teeth with less remaining tooth structure. These findings are in agreement with the recent literature33,34 reporting that risk increases by 30% to 40% for every extra missing wall,33 and also composite resins fail 3.3 times more often in posterior teeth with fewer than 2 remaining walls than those with 4 remaining walls.35 Also, another study found that multiple-surface amalgams failed more often than single-surface ones.32 Regarding the overall completeness and applicability of the evidence in this review, the included RCTs Afrashtehfar et al

compared different composite resin brands,3,4,6 amalgams with composite resins,2 and different amalgams.5 RCTs in prosthodontics are uncommon36-38 and often classified as “low quality,”39 which is why we included observational studies to obtain data for a wider range of clinical scenarios. However, observational studies provide weaker evidence than RCTs, and for this reason, our discussion prioritized the data obtained from RCTs whenever possible. Also, to improve the quality of reporting outcomes of this review, the WAM of RCTs and observational studies were reported both separately and combined (Fig. 3). The follow-up period of the studies included ranged from 3 to 7 years. This was an important strength in this review because shorter studies have limited clinical relevance as most acceptable materials remain failurefree during the first few years.19,32,40 The analysis of failure rate was also a strength of this review because it is a definitive outcome that reflects an unequivocal benefit THE JOURNAL OF PROSTHETIC DENTISTRY

8

to the patient and may directly affect clinical practice and public health policies.41 A weakness of this study was the variability in the failure rate outcomes among the observational studies because of the differences in settings, age of participants, caries risk, and teeth assessed (premolars versus molars). Indeed, in this review, premolar teeth were not analyzed separately from molars because the data found in most of the included these studies did not differentiate between them, although premolars tend to have less salvageable tooth structure than molars.32 Also, differences in the liners/bases and adhesives used may have influenced the results of the composite resin studies. Another potential source of bias is that the USPHS criteria may not have been consistently applied across studies.42 In addition, even though most of the studies detailed the training and experience of the operators, they were conducted mainly in university settings (8 of 14) and in Europe (10 of 14); consequently, it is difficult to generalize the findings to other settings and regions. In addition, the quality of reporting in the observational studies was low (Supplemental Table 10, Table 2), and the overall level of evidence from the included studies was moderate in 2 RCTs4,6 and low (C) in the rest of studies. Regarding the quality of the evidence, this review presents some degree of uncertainty, since the studies included presented some risk of bias. Sample size calculations were neither conducted nor reported, and considerable variation was found in the methodology and quality of the studies (Table 2; Fig. 2A). Another weakness in the included studies was the lack of blinding of both operators and evaluators; this is often unavoidable in restorative dentistry RCTs (unlike other disciplines) (Fig. 2) because the material and clinical protocol are impossible to conceal; and patient input could also affect allocation concealment.41 Regarding the review process, the search strategy was developed by 2 experienced librarians and 2 reviewers who scrutinized all identified references independently. However, the possibility that some references have been missed cannot be excluded. Additionally, the manual search of cross-references, relevant journals, and reviews, and the data extraction was done by only 1 reviewer (K.I.A.) (Supplemental Table 11). This review has both clinical and research implications because it can help clinicians make better-informed decisions upon planning restorations of posterior vital teeth, and it provides insight into areas of future research. Future clinical studies should be performed following the recommended guidelines (STROBE and CONSORT) and across a wider range of settings including students, professors, and clinicians from private and public practices.43,44 Additionally, treatment outcomes should be assessed as a function of a larger number of risk factors45 over a suitable follow-up period and should report failure THE JOURNAL OF PROSTHETIC DENTISTRY

Volume

-

Issue

-

based on reproducible and valid tools such as the USPHS. Also, given the proposed discontinuation of amalgam, the long-term performance of new composite resin materials should be investigated.30 CONCLUSIONS Despite its limitations, our study shows that restorations in posterior vital teeth should be planned according to the amount of remaining tooth structure because of the relationship with failure rate. In terms of treatment selection, direct restorations are a valid option in posterior vital teeth with 2 or more remaining coronal walls; however, crowns may be preferred in teeth with less remaining structure. Regardless of the amount of remaining tooth structure in posterior teeth, amalgam seems to perform better than composite resin. Additionally, our results encourage improvements in the reporting and standardization of primary studies to provide more meaningful comparisons among restorative interventions. REFERENCES 1. Sweet M, Damiano P, Rivera E, Kuthy R, Heller K. A comparison of dental services received by Medicaid and privately insured adult populations. J Am Dent Assoc 2005;136:93-100. 2. Bernardo M, Luis H, Martin MD, Leroux BG, Rue T, Leitao J, et al. Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. J Am Dent Assoc 2007; 138:775-83. 3. Kramer N, Garcia-Godoy F, Reinelt C, Feilzer AJ, Frankenberger R. Nanohybrid vs. fine hybrid composite in extended class II cavities after six years. Dent Mater 2011;27:455-64. 4. Manhart J, Chen HY, Hickel R. Clinical evaluation of the posterior composite Quixfil in class I and II cavities: 4-year follow-up of a randomized controlled trial. J Adhes Dent 2010;12:237-43. 5. Plasmans PJ, van ’t Hof MA. A 4-year clinical evaluation of extensive amalgam restorationsedescription of the failures. J Oral Rehabil 1993;20: 561-70. 6. Shi L, Wang X, Zhao Q, Zhang Y, Zhang L, Ren Y, et al. Evaluation of packable and conventional hybrid resin composites in class I restorations: three-year results of a randomized, double-blind and controlled clinical trial. Oper Dent 2010;35:11-9. 7. Akerboom HB, Advokaat JG, Van Amerongen WE, Borgmeijer PJ. Long-term evaluation and rerestoration of amalgam restorations. Community Dent Oral Epidemiol 1993;21:45-8. 8. Kiremitci A, Alpaslan T, Gurgan S. Six-year clinical evaluation of packable composite restorations. Oper Dent 2009;34:11-7. 9. Kohler B, Rasmusson CG, Odman P. A five-year clinical evaluation of class II composite resin restorations. J Dentistry 2000;28:111-6. 10. Kolker JL, Damiano PC, Armstrong SR, Bentler SE, Flach SD, Caplan DJ, et al. Natural history of treatment outcomes for teeth with large amalgam and crown restorations. Oper Dent 2004;29:614-22. 11. Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci 2012;120: 539-48. 12. Lin H, Wang J, Yan W. [A three-year clinical evaluation of five light-cured composite resins in fillings of posterior teeth]. Zhonghua Kou Qiang Yi Xue Za Zhi 1997;32:242-5. 13. Lucarotti PS, Holder RL, Burke FJ. Analysis of an administrative database of half a million restorations over 11 years. J Dent 2005;33:791-803. 14. Mjor IA, Jokstad A. Five-year study of Class II restorations in permanent teeth using amalgam, glass polyalkenoate (ionomer) cement and resin-based composite materials. J Dent 1993;21:338-43. 15. Opdam NJ, Loomans BA, Roeters FJ, Bronkhorst EM. Five-year clinical performance of posterior resin composite restorations placed by dental students. J Dent 2004;32:379-83. 16. Morgano SM, Rodrigues AH, Sabrosa CE. Restoration of endodontically treated teeth. Dent Clin North Am 2004;48:397-416. 17. Opdam NJ, Bronkhorst EM, Loomans BA, Huysmans MC. 12-year survival of composite vs. amalgam restorations. J Dent Res 2010;89:1063-7.

Afrashtehfar et al

-

2016

18. Trushkowsky RD. Restoration of endodontically treated teeth: criteria and technique considerations. Quintessence Int 2014;45:557-67. 19. Demarco FF, Correa MB, Cenci MS, Moraes RR, Opdam NJ. Longevity of posterior composite restorations: not only a matter of materials. Dent Mater 2012;28:87-101. 20. Kawata T, Kawaguchi T, Yoda N, Ogawa T, Kuriyagawa T, Sasaki K. Effects of a removable partial denture and its rest location on the forces exerted on an abutment tooth in vivo. Int J Prosthodont 2008;21:50-2. 21. Hapcook CP Sr. Dental malpractice claims: percentages and procedures. J Am Dent Assoc 2006;137:1444-5. 22. Grembowski D, Fiset L, Milgrom P, Forrester K, Spadafora A. Factors influencing the appropriateness of restorative dental treatment: an epidemiologic perspective. J Public Health Dent 1997;57:19-30. 23. Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, et al. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. Syst Rev 2015;4:1. 24. Heintze SD, Rousson V. Clinical effectiveness of direct class II restorationsda meta-analysis. J Adhes Dent 2012;14:407-31. 25. Viera AJ, Garrett JM. Understanding interobserver agreement: the kappa statistic. Fam Med 2005;37:360-3. 26. SAS Institute Inc. Base SAS 9.3 procedures guide. Cary, NC: SAS Institute Inc.; 2011:72-233. 27. Armola RR, Bourgault AM, Halm MA, Board RM, Bucher L, Harrington L, et al. Upgrading the American Association of Critical-Care Nurses’ evidenceleveling hierarchy. Am J Crit Care 2009;18:405-9. 28. Olmos M, Antelo M, Vazquez H, Smecuol E, Maurino E, Bai JC. Systematic review and meta-analysis of observational studies on the prevalence of fractures in coeliac disease. Dig Liver Dis 2008;40:46-53. 29. Afrashtehfar KI, Assery MK. Five considerations in cosmetic and esthetic dentistry. J N J Dent Assoc 2014;85:14-5. 30. Rasines Alcaraz MG, Veitz-Keenan A, Sahrmann P, Schmidlin PR, Davis D, Iheozor-Ejiofor Z. Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth. Cochrane Database Syst Rev 2014;3: CD005620. 31. Lyons K. Ministry of H. Direct placement restorative materials for use in posterior teeth: the current options. N Z Dent J 2003;99:10-5. 32. Frencken JE, Sithole WD. National oral health survey Zimbabwe 1995: quality of restorations. SADJ 1998;53:435-8. 33. Opdam NJ, van de Sande FH, Bronkhorst E, Cenci MS, Bottenberg P, Pallesen U, et al. Longevity of posterior composite restorations: a systematic review and meta-analysis. J Dent Res 2014;93:943-9. 34. Moura FR, Romano AR, Lund RG, Piva E, Rodrigues Junior SA, Demarco FF. Three-year clinical performance of composite restorations placed by undergraduate dental students. Braz Dent J 2011;22:111-6. 35. da Rosa Rodolpho PA, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;34:427-35.

Afrashtehfar et al

9

36. Contrepois M, Soenen A, Bartala M, Laviole O. Marginal adaptation of ceramic crowns: a systematic review. J Prosthet Dent 2013; 110:447-54.e10. 37. Takeichi T, Katsoulis J, Blatz MB. Clinical outcome of single porcelain-fusedto-zirconium dioxide crowns: a systematic review. J Prosthet Dent 2013;110: 455-61. 38. Lang LA, Teich ST. A critical appraisal of the systematic review process: systematic reviews of zirconia single crowns. J Prosthet Dent 2014;111: 476-84. 39. Pandis N, Polychronopoulou A, Eliades T. An assessment of quality characteristics of randomised control trials published in dental journals. J Dent 2010;38:713-21. 40. Manhart J, Chen H, Hamm G, Hickel R. Buonocore Memorial Lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. Oper Dent 2004;29:481-508. 41. Bidra AS. Evidence-based prosthodontics: fundamental considerations, limitations, and guidelines. Dent Clin North Am 2014;58:1-17. 42. Chadwick B, Treasure E, Dummer P, Dunstan F, Gilmour A, Jones R, et al. Challenges with studies investigating longevity of dental restorationsea critique of a systematic review. J Dent 2001;29:155-61. 43. von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP, et al. The Strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med 2007;4:e296. 44. Moher D, Schulz KF, Altman DG, Group C. The CONSORT statement: revised recommendations for improving the quality of reports of parallelgroup randomised trials. Clin Oral Investig 2003;7:2-7. 45. Afrashtehfar KI, Eimar H, Yassine R, Abi-Nader S, Tamimi F. Evidence-based dentistry for planning restorative treatments: barriers and potential solutions. Eur J Dent Educ http://dx.doi.org/10.1111/eje.12208. [Epub ahead of print]. Corresponding author: Dr Faleh Tamimi Faculty of Dentistry, McGill University Room M64, 3640 University Street Montreal, QC CANADA Email: [email protected] Acknowledgments The authors thank librarians A. Lambreau, McGill University, and P. DuPont, University of Montréal, for their assistance in designing the electronic search strategies; and doctoral student O. Eilayyan, McGill University Faculty of Medicine, for conducting the statistical analysis. Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.

THE JOURNAL OF PROSTHETIC DENTISTRY

9.e1

Volume

-

Issue

-

SUPPLEMENTAL MATERIAL

REFERENCES

METHODOLOGY Data extraction The following data were extracted and recorded by 1 reviewer (K.I.A.) into an electronic spreadsheet: names of authors, year of publication, country of the trial, study design, years of follow-up, characteristics of participants (age, gender, setting), drop-outs, type of restoration (prostheses, dental fillings), materials used in the restoration (amalgams, resins, and so on), tooth localization (molar, premolar, maxillary, mandibular), and outcomes. Lastly, based on the restoration material, the data (n restorations, % failure) from the studies was categorized into groups according to remaining tooth structure prior to restoration. When important data were missing, a reviewer (K.I.A.) attempted to contact the publications’ authors to resolve ambiguity. However, only authors from 2 studies added relevant information.1,2 For the trials with multiple reports, only the outcome data from the most recent report were assigned as the main study.

1. Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci 2012;120: 539-48. 2. Mjor IA, Jokstad A. Five-year study of class II restorations in permanent teeth using amalgam, glass polyalkenoate (ionomer) cerment and resin-based composite materials. J Dent 1993;21:338-43. 3. Higgins JPT, Green S; Cochrane Collaboration. Cochrane handbook for systematic reviews of interventions. Hoboken NJ: Wiley-Blackwell; 2012. 4. Emami E, Heydecke G, Rompre PH, de Grandmont P, Feine JS. Impact of implant support for mandibular dentures on satisfaction, oral and general health-related quality of life: a meta-analysis of randomized-controlled trials. Clin Oral Implants Res 2009;20:533-44. 5. de Souza RF, Ahmadi M, Ribeiro AB, Emami E. Focusing on outcomes and methods in removable prosthodontics trials: a systematic review. Clin Oral Implants Res 2014;25:1137-41. 6. Ebell MH, Siwek J, Weiss BD, Woolf SH, Susman J, Ewigman B, et al. Strength of recommendation taxonomy (SORT): a patient-centered approach to grading evidence in the medical literature. Am Fam Physician 2004;69: 548-56. 7. von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP, et al. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med 2007;4:e296. 8. Olmos M, Antelo M, Vazquez H, Smecuol E, Maurino E, Bai JC. Systematic review and meta-analysis of observational studies on the prevalence of fractures in coeliac disease. Dig Liver Dis 2008;40:46-53. 9. Armola RR, Bourgault AM, Halm MA, Board RM, Bucher L, Harrington L, et al. Upgrading the American Association of Critical-Care Nurses’ evidenceleveling hierarchy. Am J Crit Care 2009;18:405-9. 10. Al-Samhan A, Al-Enezi H, Alomari Q. Clinical evaluation of posterior resin composite restorations placed by dental students of Kuwait University. Med Princ Pract 2010;19:299-304. 11. Burke FJT. Four year performance of dentine-bonded all-ceramic crowns. Br Dent J 2007;202:269-73. 12. Busato AL, Loguercio AD, Reis A, Carrilho MR. Clinical evaluation of posterior composite restorations: 6-year results. Am J Den 2001;14:304-8. 13. Cloyd S, Gilpatrick RO, Moore D. Preventive resin restorations vs. amalgam restorations: a three-year clinical study. J Tenn Dent Assoc 1997; 77:36-40. 14. da Rosa Rodolpho PA, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;34:427-35. 15. Ferrari M, Cagidiaco MC, Goracci C, Vichi A, Mason PN, Radovic I, et al. Long-term retrospective study of the clinical performance of fiber posts. Am J Den 2007;20:287-91. 16. Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay FR, Breschi L, et al. A randomized controlled trial of endodontically treated and restored premolars. J Dent Res 2012;91:72S-8S. 17. Frankenberger R, Reinelt C, Kramer N. Nanohybrid vs. fine hybrid composite in extended class II cavities: 8-year results. Clin Oral Investig 2014;18:125-37. 18. Frencken JE, Sithole WD. National oral health survey Zimbabwe 1995: quality of restorations. SADJ 1998;53:435-8. 19. Gungor MA, Artunc C, Dundar M. Seven-year clinical follow-up study of Probond ceramic crowns. Quintessence Int 2007;38:e456-63. 20. Kreulen CM, van Amerongen WE, Akerboom HB, Borgmeijer PJ, Gruythuysen RJ. Evaluation of occlusal marginal adaptation of Class II resincomposite restorations. ASDC J Dent Child 1993;60:310-4. 21. Kubo S, Kawasaki A, Hayashi Y. Factors associated with the longevity of resin composite restorations. Dent Mater 2011;30:374-83. 22. Letzel H, van ’t Hof MA, Marshall GW, Marshall SJ. The influence of the amalgam alloy on the survival of amalgam restorations: a secondary analysis of multiple controlled clinical trials. J Dent Res 1997;76:1787-98. 23. Mair LH. Ten-year clinical assessment of three posterior resin composites and two amalgams. Quintessence Int 1998;29:483-90. 24. Mancebo JC, Jimenez-Castellanos E, Canadas D. Effect of tooth type and ferrule on the survival of pulpless teeth restored with fiber posts: a 3-year clinical study. Am J Den 2010;23:351-6. 25. Mannocci F, Bertelli E, Sherriff M, Watson TF, Ford TR. Three-year clinical comparison of survival of endodontically treated teeth restored with either full cast coverage or with direct composite restoration. J Prosthet Dent 2002;88:297-301. 26. Mannocci F, Qualtrough AJ, Worthington HV, Watson TF, Pitt Ford TR. Randomized clinical comparison of endodontically treated teeth restored with amalgam or with fiber posts and resin composite: five-year results. Oper Dent 2005;30:9-15. 27. Moura FR, Romano AR, Lund RG, Piva E, Rodrigues Junior SA, Demarco FF. Three-year clinical performance of composite restorations placed by undergraduate dental students. Braz Dent J 2011;22:111-6. 28. Nikaido T, Takada T, Kitasako Y, Ogata M, Shimada Y, Yoshikawa T, et al. Retrospective study of the 10-year clinical performance of direct resin

Quality assessment and risk of bias Two independent reviewers (K.I.A., M.A.) carried out the methodological quality assessment on the basis of the type of the study. For randomized controlled trials, the methodological quality of the trials was assessed using a domain-based evaluation (Cochrane Collaboration tool), including reports of sample size estimation and 5 parameters of quality: sequence generation, allocation concealment, completeness of follow-up, intention-to-treat analysis, and masking/blinding.3,4 Each parameter of trial methodological quality was graded as: “adequate,” “inadequate,” “unclear,” or “not applicable.”5 Studies were defined as having a low-risk of bias if the 5 criteria listed above were clearly met in the study. If 1 or more of these criteria was not met, a study would be considered as having a moderate or high potential risk of bias, respectively. As an additional measure for the completeness of follow-up parameter, studies with more than 20% attrition were considered to be “inadequate.”6 For the observational studies, the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) statement was used to assess the study.7 STROBE provides a checklist with 22 items such as prespecified hypothesis, sample size estimation, and reasons for dropout. Additionally, each study was categorized according to the Olmos classification, where A = high level, that is, the study is in agreement with more than 80% of the STROBE criteria; B = moderate level, that is, 50%-80% of STROBE criteria were fulfilled; and C = low level, that is, less than 50% criteria could be achieved.8 Finally, the level of evidence in the included studies was assessed using the American Association of Critical Care Nurses” (ACCN) new evidence-leveling system.9 THE JOURNAL OF PROSTHETIC DENTISTRY

Afrashtehfar et al

-

29. 30. 31. 32.

33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44.

45.

2016

composite restorations placed with the acid-etch technique. Quintessence Int 2007;38:e240-6. Pazinatto FB, Gionordoli Neto R, Wang L, Mondelli J, Mondelli RF, Navarro MF. 56-month clinical performance of Class I and II resin composite restorations. J Appl Oral Sci 2012;20:323-8. Peutzfeldt A, Sahafi A, Asmussen E. A survey of failed post-retained restorations. Clin Oral Investig 2008;12:37-44. Sarrett DC, Brooks CN, Rose JT. Clinical performance evaluation of a packable posterior composite in bulk-cured restorations. J Am Dent Assoc 2006;137: 71-80. Signore A, Kaitsas V, Ravera G, Angiero F, Benedicenti S. Clinical evaluation of an oval-shaped prefabricated glass fiber post in endodontically treated premolars presenting an oval root canal cross-section: a retrospective cohort study. Int J Prosthodont 2011;24:255-63. Smales RJ, Webster DA. Restoration deterioration related to later failure. Oper Dent 1993;18:130-7. Sunnegardh-Gronberg K, van Dijken JW, Funegard U, Lindberg A, Nilsson M. Selection of dental materials and longevity of replaced restorations in Public Dental Health clinics in northern Sweden. J Dent 2009;37:673-8. Tobi H, Kreulen CM, Vondeling H, van Amerongen WE. Cost-effectiveness of composite resins and amalgam in the replacement of amalgam class II restorations. Community Dent Oral Epidemiol 1999;27:137-43. Turkun LS, Aktener BO, Ates M. Clinical evaluation of different posterior resin composite materials: a 7-year report. Quintessence Int 2003;34:418-26. van Dijken JW, Pallesen U. A six-year prospective randomized study of a nano-hybrid and a conventional hybrid resin composite in Class II restorations. Dent Mater 2013;29:191-8. Adolphi G, Zehnder M, Bachmann LM, Gohring TN. Direct resin composite restorations in vital versus root-filled posterior teeth: a controlled comparative long-term follow-up. Oper Dent 2007;32:437-42. Collins CJ, Bryant RW, Hodge KL. A clinical evaluation of posterior composite resin restorations: 8-year findings. J Dent 1998;26:311-7. Dammaschke T, Nykiel K, Sagheri D, Schafer E. Influence of coronal restorations on the fracture resistance of root canal-treated premolar and molar teeth: a retrospective study. Aust Endod J 2013;39:48-56. Fokkinga WA, Kreulen CM, Bronkhorst EM, Creugers NH. Composite resin core-crown reconstructions: an up to 17-year follow-up of a controlled clinical trial. Int J Prosthodont 2008;21:109-15. Geurtsen W, Schoeler U. A 4-year retrospective clinical study of Class I and Class II composite restorations. J Dent 1997;25:229-32. Gomez-Polo M, Llido B, Rivero A, Del Rio J, Celemin A. A 10-year retrospective study of the survival rate of teeth restored with metal prefabricated posts versus cast metal posts and cores. J Dent 2010;38:916-20. Hikasa T, Matsuka Y, Mine A, Minakuchi H, Hara ES, Van Meerbeek B, et al. A 15-year clinical comparative study of the cumulative survival rate of cast metal core and resin core restorations luted with adhesive resin cement. Int J Prosthodont 2010;23:397-405. Janus CE, Unger JW, Best AM. Survival analysis of complete veneer crowns vs. multisurface restorations: a dental school patient population. J Dent Educ 2006;70:1098-104.

Afrashtehfar et al

9.e2

46. Juloski J, Fadda GM, Monticelli F, Fajo-Pascual M, Goracci C, Ferrari M. Fouryear Survival of Endodontically Treated Premolars Restored with Fiber Posts. J Dent Res 2014;93:52S-8S. 47. Laegreid T, Gjerdet NR, Johansson AK. Extensive composite molar restorations: 3 years clinical evaluation. Acta Odontol Scand 2012;70:344-52. 48. Lundin SA, Koch G. Class I and II posterior composite resin restorations after 5 and 10 years. Swed Dent J 1999;23:165-71. 49. Miyamoto T, Morgano SM, Kumagai T, Jones JA, Nunn ME. Treatment history of teeth in relation to the longevity of the teeth and their restorations: outcomes of teeth treated and maintained for 15 years. J Prosthet Dent 2007;97:150-6. 50. Nagasiri R, Chitmongkolsuk S. Long-term survival of endodontically treated molars without crown coverage: a retrospective cohort study. J Prosthet Dent 2005;93:164-70. 51. Naumann M, Koelpin M, Beuer F, Meyer-Lueckel H. 10-year survival evaluation for glass-fiber-supported postendodontic restoration: a prospective observational clinical study. J Endod 2012;38:432-5. 52. Nordbo H, Leirskar J, von der Fehr FR. Saucer-shaped cavity preparations for posterior approximal resin composite restorations: observations up to 10 years. Quintessence Int 1998;29:5-11. 53. Opdam NJ, Bronkhorst EM, Roeters JM, Loomans BA. Longevity and reasons for failure of sandwich and total-etch posterior composite resin restorations. J Adhes Dent 2007;9:469-75. 54. Palaniappan S, Elsen L, Lijnen I, Peumans M, Van Meerbeek B, Lambrechts P. Nanohybrid and microfilled hybrid versus conventional hybrid composite restorations: 5-year clinical wear performance. Clin Oral Investig 2012;16:181-90. 55. Rasmusson CG, Lundin SA. Class II restorations in six different posterior composite resins: five-year results. Swed Dent J 1995;19:173-82. 56. Schmitter M, Hamadi K, Rammelsberg P. Survival of two post systemsefiveyear results of a randomized clinical trial. Quintessence Int 2011;42:843-50. 57. Simecek JW, Diefenderfer KE, Cohen ME. An evaluation of replacement rates for posterior resin-based composite and amalgam restorations in U.S. Navy and marine corps recruits. J Am Dent Assoc 2009;140:200-9; quiz 49. 58. Smales RJ, Hawthorne WS. Long-term survival and cost-effectiveness of five dental restorative materials used in various classes of cavity preparations. Int Dent J 1996;46:126-30. 59. Smales RJ, Hawthorne WS. Long-term survival of extensive amalgams and posterior crowns. J Dent 1997;25:225-7. 60. Sterzenbach G, Franke A, Naumann M. Rigid versus flexible dentine-like endodontic postseclinical testing of a biomechanical concept: seven-year results of a randomized controlled clinical pilot trial on endodontically treated abutment teeth with severe hard tissue loss. J Endod 2012;38:1557-63. 61. Torres CR, Borges AB, Goncalves SE, Pucci CR, de Araujo MA, Barcellos DC. Clinical evaluation of two packable resin-based composite restorations: a three-year report. Gen Dent 2010;58:338-43. 62. Turkun LS, Turkun M, Ozata F. Clinical performance of a packable resin composite for a period of 3 years. Quintessence Int 2005;36:365-72. 63. Van Nieuwenhuysen JP, D’Hoore W, Carvalho J, Qvist V. Long-term evaluation of extensive restorations in permanent teeth. J Dent 2003;31:395-405.

THE JOURNAL OF PROSTHETIC DENTISTRY

9.e3

Volume

-

Issue

-

Supplemental Table 1. Search strategy used for Cochrane Oral Health Group’s Trials Register (longevity or success or failure or repair or prognos* or survival or follow-up or follow up) AND (resin* or compomer* or composite* or amalgam* or “direct restor* or “conventional fill*” or “dental filling*” or crown* or full cast*) AND (dental or dentition or tooth)

Supplemental Table 2. Search strategy used for CENTRAL 1. Longevity 2. ([Exp TREATMENT OUTCOME]) or (success]) 3. (DENTAL RESTORATION FAILURE) or (failure) 4. DENTAL STRESS ANALYSIS 5. ([prognos*) or (Exp PROGNOSIS]) 6. ([Exp SURVIVAL ANALYSIS) or (Survival]) 7. FOLLOW UP STUDIES

8. DENTAL PROSTHESIS REPAIR 9. (#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8) 10. DENTAL AMALGAM 11. ([RESINS) or (COMPOSITE RESINS) or (COMPOMERS) or (Exp EPOXY RESINS]) 12. resin* 13. composite* 14. compomer* 15. amalgam*

16. 17. 18. 19. 20. 21.

direct restor* conventional fill* dental filling* ([crown*) or (Exp CROWNS]) full cast* (#10 or #11 or #12 or #13 or #15 or #16 or #17 or #18 or #19 or #20) 22. ([DENTAL RESTORATION) or (DENTITION) or (TOOTH]) #23 #9 AND #21 AND #22

CENTRAL, Cochrane Central Register of Controlled Trials. Asterisk (*) used as truncation symbol.

Supplemental Table 3. Search strategy used for OVID MEDLINE + EPOCa 1. longevity.mp. 2. exp Treatment Outcome/ or success.mp. 3. Dental Restoration Failure/ or failure.mp. 4. Dental Prosthesis Repair/ 5. Dental Stress Analysis/ 6. prognos$.mp. or exp Prognosis/ 7. exp Survival Analysis/ or Survival.mp. 8. Follow-Up Studies/ 9. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 10. Dental Amalgam/ 11. Resins, Synthetic/ or Composite Resins/ or Compomers/ or exp Epoxy Resins/

12. 13. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

resin$.mp. composite$.mp. resin$.mp. composite$.mp. compomer$.mp. amalgam$.mp. “direct restor$”.mp. “conventional fill$”.mp. “dental filling$”.mp. crown$.mp. or exp Crowns/ full cast$.mp. 10 or 11 or 12 or 13 or 15 or 16 or 17 or 18 or 19 or 20 22. dentistry, operative/ or dental restoration, permanent/ or dentition/ or tooth/

23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35.

9 and 21 and 22 randomized controlled trial.pt. controlled clinical trial.pt. randomized.ab. placebo.ab. clinical trials as topic.sh. randomly.ab. trial.ab. 24 or 25 or 26 or 27 or 28 or 29 or 30 exp animals/ not humans.sh. 31 not 32 23 and 33 limit 34 to yr=“1993 - 2015”

a

MEDLINE, sensitivity- and precision-maximizing version (2008 revision Box 6.4d http://www.cochrane-handbook.org/).

Supplemental Table 4. Search strategy used for Embase, 1947 to February 2015 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

longevity.mp. exp treatment outcome/ success.mp. failure*.mp. exp prognosis/ or prognos*.mp. survival.mp. or exp survival/ exp follow up/ durab*.mp. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 exp amalgam/ resin/ or compomer/ or epoxy resin/ compomer/ or epoxy resin/ resin*.mp. composite*.mp. compomer*.mp.

16. 17. 18. 19. 20. 21. 22. 23.

24. 25. 26. 27. 28. 29.

amalgam*.mp. “conventional fill*”.mp. “direct restor*”.mp. “dental filling*”.mp. crown*.mp. exp tooth crown/ full cast*.mp. 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 dental surgery/ 9 and 23 and 24 Randomized controlled trial/ random$.tw. experiment$.tw. (time adj series).tw.

30. (pre test or pretest or post test or posttest).tw. 31. impact.tw. 32. intervention$.tw. 33. chang$.tw. 34. evaluat$.tw. 35. effect?.tw. 36. compar$.tw. 37. control$.tw. 38. Nonhuman/ 39. or/26-37 40. 39 not 38 41. 25 and 40 42. limit 41 to yr=“1993-2015”

Supplemental Table 5. Method information 1: journals selected for hand searching Journal of Prosthodontics International Journal of Prosthodontics Journal of Prosthetic Dentistry The International Journal of Periodontics and Restorative Dentistry Journal of Dental Research Operative Dentistry Journal of the American Dental Association Journal of Dentistry

THE JOURNAL OF PROSTHETIC DENTISTRY

Afrashtehfar et al

-

2016

9.e4

Supplemental Table 6. Full-text excluded articles and reasons for exclusion Reason for Exclusion

Articles Excluded

Not meeting inclusion criteriaa

Al-Samhan et al10 (2010) Burke11 (2007) Busato et al12 (2001) Cloyd et al13 (1997) da Rosa Rodolpho et al14 (2006) Ferrari et al15 (2007) Ferrari et al16 (2012) Frankenberger et al17 (2014) Frencken and Sithole18 (1998) Gungor et al19 (2007) Kreulen et al20 (1993) Kubo et al21 (2011) Letzel et al22 (1997) Mair23 (1998)

Mancebo et al24 (2010) Mannocci et al25 (2002) Mannocci et al26 (2005) Moura et al27 (2011) Nikaido et al28 (2007) Pazinatto et al29 (2012) Peutzfeldt et al30 (2008) Sarrett et al31 (2006) Signore et al32 (2011) Smales and Webster33 (1993) Sunnegardh-Gronberg et al34 (2009) Tobi et al35 (1999) Turkun et al36 (2003) van Dijken and Pallesen37 (2013)

Inadequate datab

Adolphi et al38 (2007) Collins et al39 (1998) Dammaschke et al40 (2013) Fokkinga et al41 (2008) Geurtsen and Schoeler42 (1997) Gomez-Polo et al43 (2010) Hikasa et al44 (2010) Janus et al45 (2006) Juloski et al46 (2014) Laegreid et al47 (2012) Lundin and Koch48 (1999) Miyamoto et al49 (2007) Nagasiri and Chitmongkolsuk50 (2005)

Naumann et al51 (2012) Nordbo et al52 (1998) Opdam et al53 (2007) Palaniappan et al54 (2012) Rasmusson and Lundin55 (1995) Schmitter et al56 (2011) Simecek et al57 (2009) Smales and Hawthorne58 (1996) Smales and Hawthorne59 (1997) Sterzenbach et al60 (2012) Torres et al61 (2010) Turkun et al62 (2005) Van Nieuwenhuysen et al63 (2003)

a Not meeting inclusion criteria: included articles which had unknown vitality status or only nonvital teeth no information on remaining walls, or were review articles. bInadequate data: “Data non extractable” included articles which grouped surface information, no information combining remaining walls with restorative material and included bruxers, fixed dental prostheses (FDPs), and nontraditional types of restoration (saucer-shaped). “Invalid remaining structure description” included articles which were not describing coronal remaining walls or restored surfaces (e.g. >75% dentine wall circumferential, 1 cusp covered filling size, at least 40% of the crown had to be destroyed).

Afrashtehfar et al

THE JOURNAL OF PROSTHETIC DENTISTRY

9.e5

Volume

-

Issue

-

Supplemental Table 7. References to studies included in this review Akerboom 1993 * Akerboom HB, Advokaat JG, Van Amerongen WE, Borgmeijer PJ. Long-term evaluation and rerestoration of amalgam restorations. Community Dent Oral Epidemiol 1993;21(1):45-8. Gruythuysen RJ, Kreulen CM, Tobi H, van Amerongen E, Akerboom HB. 15-year evaluation of Class II amalgam restorations. Community Dent Oral Epidemiol 1996;24(3):207-10. Kreulen CM, Tobi H, Gruythuysen RJ, van Amerongen WE, Borgmeijer PJ. Replacement risk of amalgam treatment modalities: 15-year results. J Dent 1998;26(8):627-32. Bernardo 2007 Bernardo M, Luis H, Martin MD, et al. Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. J Am Dent Assoc 2007;138(6):775-83. Kiremitci 2009 Kiremitci A, Alpaslan T, Gurgan S. Six-year clinical evaluation of packable composite restorations. Oper Dent 2009;34(1):11-7. Kramer 2011 Kramer N, Reinelt C, Richter G, Petschelt A, Frankenberger R. Nanohybrid vs. fine hybrid composite in Class II cavities: clinical results and margin analysis after four years. Dent Mater 2009;25(6):750-9. * Kramer N, Garcia-Godoy F, Reinelt C, Feilzer AJ, Frankenberger R. Nanohybrid vs. fine hybrid composite in extended Class II cavities after six years. Dent Mater 2011;27(5):455-64. Kohler 2000 Rasmusson CG, Kohler B, Odman P. A 3-year clinical evaluation of two composite resins in class-II cavities. Acta Odontol Scand 1998;56(2):70-5. * Kohler B, Rasmusson CG, Odman P. A five-year clinical evaluation of Class II composite resin restorations. J Dent 2000;28(2):111-6. Kolker 2004 * Kolker JL, Damiano PC, Armstrong SR, et al. Natural history of treatment outcomes for teeth with large amalgam and crown restorations. Oper Dent 2004;29(6):614 -22. Kolker JL, Damiano PC, Jones MP, et al. The timing of subsequent treatment for teeth restored with large amalgams and crowns: factors related to the need for subsequent treatment. J Dent Res 2004;83(11):854-8. Kolker JL, Damiano PC, Caplan DJ, et al. Teeth with large amalgam restorations and crowns: factors affecting the receipt of subsequent treatment after 10 years. J Am Dent Assoc 2005;136(6):738-48; quiz 805-6. † Kopperud 2012 Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci 2012;120(6):539-48. Lin 1997 Lin H, Wang J, Yan W. [A three-year clinical evaluation of five light-cured composite resins in fillings of posterior teeth]. Zhonghua Kou Qiang Yi Xue Za Zhi 1997;32(4):242-5. Lucarotti 2005 Burke FJ, Lucarotti PS. How long do direct restorations placed within the general dental services in England and Wales survive? Br Dent J 2009;206(1): E2; discussion 26-7. * Lucarotti PS, Holder RL, Burke FJ. Analysis of an administrative database of half a million restorations over 11 years. J Dent 2005;33(10):791-803. Burke FJ, Lucarotti PS, Holder R. Outcome of direct restorations placed within the general dental services in England and Wales (Part 4): influence of time and place. J Dent 2005;33(10):837-47. Burke FJ, Lucarotti PS, Holder RL. Outcome of direct restorations placed within the general dental services in England and Wales (Part 2): variation by patients’ characteristics. J Dent 2005;33(10):817-26. Lucarotti PS, Holder RL, Burke FJ. Outcome of direct restorations placed within the general dental services in England and Wales (Part 3): variation by dentist factors. J Dent 2005;33(10):827-35. Lucarotti PS, Holder RL, Burke FJ. Outcome of direct restorations placed within the general dental services in England and Wales (Part 1): variation by type of restoration and re-intervention. J Dent 2005;33(10):805-15. Manhart 2010 Manhart J, Chen HY, Hickel R. Three-year results of a randomized controlled clinical trial of the posterior composite QuiXfil in class I and II cavities. Clin Oral Investig 2009;13(3):301-7. * Manhart J, Chen HY, Hickel R. Clinical evaluation of the posterior composite Quixfil in class I and II cavities: 4-year follow-up of a randomized controlled trial. J Adhes Dent 2010;12(3):237-43. Mjor 1993 Mjor IA, Jokstad A. Five-year study of Class II restorations in permanent teeth using amalgam, glass polyalkenoate (ionomer) cerment and resin-based composite materials. J Dent 1993;21(6):338-43. Opdam 2004 * Opdam NJ, Loomans BA, Roeters FJ, Bronkhorst EM. Five-year clinical performance of posterior resin composite restorations placed by dental students. J Dent 2004;32(5):379-83. Opdam NJ, Bronkhorst EM, Roeters JM, Loomans BA. A retrospective clinical study on longevity of posterior composite and amalgam restorations. Dent Mater 2007;23(1):2-8. Opdam NJ, Bronkhorst EM, Loomans BA, Huysmans MC. 12-year survival of composite vs. amalgam restorations. J Dent Res 2010;89(10):1063-7. Plasmans 1993 * Plasmans PJ, van ’t Hof MA. A 4-year clinical evaluation of extensive amalgam restorations–description of the failures. J Oral Rehabil 1993;20(6):561-70 Plasmans PJ, Creugers NH, Mulder J. Long-term survival of extensive amalgam restorations. J Dent Res 1998;77(3):453-60. Plasmans PJ, Creugers NH, Mulder J. [Long-term survival of extensive amalgam restorations]. Ned Tijdschr Tandheelkd 2000;107(6):233-7. † Shi 2010 Shi L, Wang X, Zhao Q, et al. Evaluation of packable and conventional hybrid resin composites in Class I restorations: three-year results of a randomized, double-blind and controlled clinical trial. Oper Dent 2010;35(1):11-9. *Major publication for the study (signifies key publication). †Publication inclusion from hand search origin.

THE JOURNAL OF PROSTHETIC DENTISTRY

Afrashtehfar et al

-

2016

9.e6

Supplemental Table 8. Meta regression of 5-year mean failure rates interventions in comparison to amalgam in randomized control trials Remaining Coronal Structure

Intervention

Beta-Coefficient

SE

95% CL

Z

P Value

Less than a wall Amalgam Resin

Reference 44.23

0.28

43.7

44.8

158.4

<.0001

3.77

18.2

33

6.79

<.0001

1.12

10.05

14.5

10.90

<.0001

0.25

5.1

6

22.43

<.0001

0.12

5.4

-18.8

43.14

<.0001

One wall Amalgam Resin

Reference 25.6

Two walls Amalgam Resin

Reference 12.26

Three walls Amalgam Resin

Reference 5.54

Four walls Amalgam Resin

Reference 5.15

CL, confidence limits; SE, standard error.

Supplemental Table 9. Meta regression of 5-year mean failure rates interventions in comparison to crowns according to data derived from randomized trials combined with observational studies Remaining Coronal Structure

Intervention

Beta-Coefficient

SE

95% CL

Z

P Value

Less than a wall Crown

Reference

Resin

34.90

0.00

34.90

34.90

-

-

Amalgam

26.55

0.67

25.24

27.86

39.71

<.0001

One wall Crown

Reference

Resin

8.54

1.20

6.18

10.90

7.09

<.0001

Amalgam

26.60

0.69

25.29

27.90

39.82

<.0001

CL, confidence limits; SE, standard error.

Afrashtehfar et al

THE JOURNAL OF PROSTHETIC DENTISTRY

9.e7

Volume

-

Issue

-

Supplemental Table 10. Table of quality appraisal of observational studies included in this systematic review Referenceb

Section and Topic Title and abstract

Item

Akerboom, 1993. Netherlands

Kiremitci, 2009. Turkey

Kohler, 2000. Sweden

Kolker, 2005. USA

Kopperud, 2012. Norway

Lin, 1997. China

Lucarotti, 2005. England

Mjor, 1993. Sweden

Opdam, 2004. Netherlands

1

P

P

P

Y

N

Y

Y

P

P

Introduction Background/ rationale

2

Y

Y

Y

Y

Y

Y

Y

Y

Y

Objectives

3

Y

Y

Y

Y

Y

Y

Y

Y

Y

Methods Study design

4

Y

N

N

Y

N

N

N

N

Y

Setting

5

P

N

Y

Y

Y

N

Y

N

Y

Participants

6

Y

Y

Y

Y

Y

Y

Y

Y

Y

Variables

7

N

P

P

Y

Y

P

Y

P

Y

Data sources/ measurement

8a

P

Y

Y

Y

Y

Y

Y

Y

Y

Bias

9

Y

N

N

Y

Y

N

Y

Y

N

Study size

10

N

Y

Y

Y

Y

N

Y

N

Y

Quantitative variables

11

Y

Y

Y

Y

Y

Y

Y

Y

Y

Statistical methods

12

N

Y

P

Y

Y

P

Y

Y

Y

Participants

13a

Y

Y

Y

Y

Y

P

Y

P

Y

Descriptive data

14a

Y

Y

Y

Y

Y

Y

Y

Y

Y

Outcome data

15a

Y

Y

Y

Y

Y

Y

Y

Y

Y

Main results

16

N

N

N

Y

Y

N

P

N

N

Other analyses

17

Y

N

N

Y

Y

N

N

Y

N Y

Results

Discussion Key results

18

Y

Y

Y

Y

Y

Y

Y

Y

Limitations

19

N

N

P

Y

Y

Y

Y

Y

Y

Interpretation

20

N

Y

Y

Y

Y

N

Y

N

Y

Generalizability

21

N

N

N

Y

Y

N

Y

N

Y

Other information Funding

22

Total “Y”

N

N

Y

N

Y

N

Y

N

N

11

12

13

21

20

10

19

12

17

a Gave information separately for cases and controls in case control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies. bReported classifications: N, information not provided; P, information partially provided; Y, information available.

THE JOURNAL OF PROSTHETIC DENTISTRY

Afrashtehfar et al

-

2016

9.e8

Supplemental Table 11. Reviews’ reference lists hand-searched cross-referencing Systematic reviews 1. 2. 3. 4. 5.

Downer MC, et al. How long do routine dental restorations last? A systematic review. Br Dent J 1999;187:432-9. Bolla M, et al. Root canal posts for the restoration of root filled teeth. Cochrane Database Syst Rev 2007;1:CD004623. Fedorowicz Z, et al. Single crowns versus conventional fillings for the restoration of root filled teeth. Cochrane Database Syst Rev 2012;5:CD009109. Heintze SD, Rousson V. Clinical effectiveness of direct class II restorations - a meta-analysis. J Adhes Dent 2012;14:407-31. Pjetursson BE, et al. A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. Part I: Single crowns. Clin Oral Implants Res 2007;18(suppl 3):73-85. 6. Wittneben JG, et al. A systematic review of the clinical performance of CAD/CAM single-tooth restorations. Int J Prosthodont 2009;22:466-71. 7. Heintze SD, Rousson V. Fracture rates of IPS Empress all-ceramic crowns–a systematic review. Int J Prosthodont 2010;23:129-33. 8. Wang X, et al. A systematic review of all-ceramic crowns: clinical fracture rates in relation to restored tooth type. Int J Prosthodont 2012;25:441-50. Nonsystematic reviews 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Roulet JF. Benefits and disadvantages of tooth-coloured alternatives to amalgam. J Dent 1997;25:459-73. Hickel R, et al. Clinical results and new developments of direct posterior restorations. Am J Dent2000;13(Spec No):41D-54D. Hondrum SO. The longevity of resin-based composite restorations in posterior teeth. Gen Dent 2000;48:398-404. Hickel R, Manhart J. Longevity of restorations in posterior teeth and reasons for failure. J Adhes Dent 2001;3:45-64. Jedynakiewicz NM, Martin N. Posterior restorations–a clinical view. J Adhes Dent 2001;3:101-10. Manhart J, et al. Direct posterior restorations: clinical results and new developments. Dent Clin North Am 2002;46:303-39. Manhart J, et al. Buonocore Memorial Lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. Op Dent 2004;29:481-508. Anonymous. Evidence-based review of clinical studies on restorative dentistry. J Endodont 2009;35:1111-5. Kovarik RE. Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite. Dent Clin North Am 2009;53:71-6, ix. Qvist V. Resin restorations: leakage, bacteria, pulp. Endod Dent Traumatol 1993;9:127-52. Barbakow F, et al. [Amalgam as the measure in filling therapy. A determination of its place]. Schweizer Monatsschrift fur Zahnmedizin 1994;104:1341-50. Wilson NH. The limitations of resin-bonded restorations. Annals of the Academy of Medicine, Singapore 1995;24:52-57. Eley BM. The future of dental amalgam: a review of the literature. Part 7: Possible alternative materials to amalgam for the restoration of posterior teeth. Br Dent J 1997;183:11-14. Blatz MB. Long-term clinical success of all-ceramic posterior restorations. Quintessence International 2002;33:415-26. Goodacre CJ, et al. Clinical complications in fixed prosthodontics. J Prosthet Dent 2003;90:31-41. Verrett RG, Garcia LT. The single-unit crown: factors for clinical success. Tex Dent J 2003;120:1128-35. Sarrett DC. Clinical challenges and the relevance of materials testing for posterior composite restorations. Dent Mater 2005;21:9-20. Bader JD, Shugars DA. Summary review of the survival of single crowns. Gen Dent 2009;57:74-81. Kassem AS, et al. Survival rates of porcelain molar crowns-an update. Int J Prosthodont 2010;23:60-62. Ferracane JL. Resin composite–state of the art. Dent Mater 2011;27:29-38. Demarco FF, et al. Longevity of posterior composite restorations: not only a matter of materials. Dent Mater 2012;28:87-101.

Afrashtehfar et al

THE JOURNAL OF PROSTHETIC DENTISTRY